数据库DML操作语言

术语

关键字 insert into , update,delete

作用

增加数据
insert into

修改数据
update

删除数据
delete

# =====================insert into 增加数据===============================

# 练习:新增一个student表,sid int,sname varchar(10),ssex varchar(2),sage int,
create table student(
	sid int,
	sname varchar(10),
	ssex varchar(2),
	sage int

)
desc student;
select * from student;
-- 1.插入一条数据,把列名写全
insert into student (sid,sname,ssex,sage) values (10, '张三','男',19);
-- 2.插入一条数据,列名不写
insert into student values (11,'李四','男',20);
-- 3.插入部分数据,列名写一半
insert into student (sname,ssex) values ('小丽','女');
-- 4.插入多条数据
insert into student values (15,'王五','男',22),(16,'赵六','男',25);


# ====================update 更新数据================

# 练习:修改一条数据的性别为男
-- 1.先不加where
update student set ssex = '男';
-- 2.添加where
update student set ssex = '女' where sname = '小丽';

# 注意: 修改项和条件项为同一项时需要使用嵌套方法=====

# 练习:修改年龄最小的年龄为33岁
update student set sage = 33 where sage = (select * from (select min(sage) from student) a);


# ================delete 删除表数据==================
delete from student where sname = '小丽';
delete from student;

create table student1(
	sid int,
	sname varchar(10),
	ssex varchar(2),
	sage int

)
show tables;
drop table student1;